Heretofore, catheters used in angioplasty and other dilatation type surgical procedures have generally had a conical tip. During an angioplasty procedure, a catheter is passed through the interior of a vessel to a partially obstructed or stenotic portion of the vessel. If an opening through that narrowed portion is nonexistent or too small for the cone shaped tip of the catheter to be pushed therethrough, the angioplasty procedure cannot be successfully employed. In typical angioplasty procedures, if the stenotic portion of the blood vessel can be breached by the tip of the catheter, an expandable balloon stored interiorly and rearwardly of the tapered tip may be positioned inside the stenotic portion of the vessel. The tapered tip, if made of an expandable lumen, such as found in U.S. Pat. No. 5,447,503, may be withdrawn from around the balloon. Thereafter, the balloon may be expanded by being filled with a fluid under pressure. This pressure then expands the balloon which applies pressure universally along the entire surface of the balloon and hopefully to the internal luminal wall.
This pressure, applied once or in doses, forces open the stenotic lumen in the hope that the patency of the lumen will remain open. One drawback of this instrument is that the balloon completely occludes the blood vessel in its expanded position, so its use in a surgical procedure is limited.
In my prior patent U.S. Pat. No. 5,176,128, I disclosed an organ retractor which is capable of being positioned through a trochar into a body cavity wherein it is expandable to allow the retractor to move aside and reposition organs during surgical procedures. In my copending patent application, Ser. No. 60/081,442 filed Apr. 10, 1998, I disclose an improvement in an organ retractor having a pair of hollow semi-frustoconical arms positioned around an internal stem with a mechanical means for extending the arms after that portion of the retractor has been positioned through the hollow cylindrical trochar.
Catheters for use in angioplasty are overwhelmingly of the balloon type, such as shown in the aforementioned U.S. Pat. No. 5,447,503. While these catheters may be used in blood vessels which are not completely closed, they have a limitation where stenotic portions of the vessel walls are too narrow to allow the tip to be pushed therethrough. Also, the balloon cannot function as a tip to allow it to be placed where most needed in the first instance.
A need has developed for an improved catheter tip suitable for use in angioplasty and other dilatation type surgical procedures. It is, therefore, an object of the present invention, generally stated, to provide an improved catheter with a mechanical distal end or tip.
Another object of the present invention is the provision of an improved catheter for use in connection with angioplasty and other dilatation type surgical procedures wherein the catheter is expandable while still allowing blood or other body fluids to flow through the stenotic area during the procedures.